Noninvasive stroke volume variation using electrical velocimetry for predicting fluid responsiveness in dogs undergoing cardiac surgery

Abstract

Objective: To evaluate the ability of a noninvasive cardiac output monitoring system with electrical velocimetry (EV) for predicting fluid responsiveness in dogs undergoing cardiac surgery.

Study design: Prospective experimental trial.

Animals: A total of 30 adult Beagle dogs.

Methods: Stroke volume (SV), stroke volume variation (SVV) and cardiac index were measured using the EV device in sevoflurane-anaesthetized, mechanically ventilated dogs undergoing thoracotomies for experimental creation of right ventricular failure. The dogs were considered fluid responsive if stroke volume (SVI; indexed to body weight), measured using pulmonary artery thermodilution, increased by 10% or more after volume loading (10 mL kg^-1). Relationships of SVV, central venous pressure (CVP) and pulmonary artery occlusion pressure (PAOP) with SVI were analysed to estimate fluid responsiveness.

Results: Better prediction of fluid responsiveness, with a significant area under the receiver operating characteristic curve, was observed for SVV (0.85±0.07; p=0.0016) in comparison with CVP (0.65±0.11; p=0.17) or PAOP (0.60±0.12; p=0.35), with a cut-off value of 13.5% (84% specificity and 73% sensitivity).

Conclusions and clinical relevance: SVV derived from EV is useful for identification of dogs that are likely to respond to fluids, providing valuable information on volume status under cardiothoracic anaesthesia.

Keywords: cardiac surgery; dog; electrical velocimetry; fluid therapy; haemodynamic monitoring.